Liquid fuel pump



Dec. 7, 1937. R. LORANGE LIQUID FUEL 'PUMP Filed April 20, 1935 InventorJi 0 Patented Dec. 7, 1937 UNITED STATES- LIQUID FUEL PUMP RudolfLOrange, Stuttgart, Germany, assignmof one-half to Frederick RichardSimms, London, England Application April 20, 1933, Serial No. 667,125 InGermany December 5, 1932 2 Claims.

This invention is for improvements in liquid fuel pumps of thereciprocating piston or plunger type in which a variable portion of thefuel in the pump cylinder is arranged to be discharged or by-passed fromthe cylinder under the control of the plunger through an outlet distinctfrom the normal delivery outlet, the fuel so by-passed being termed thespill and the variationinwhich is governed by rotation of the plunger inits cylinder so as to bring difierent portions of an inclined or obliquecontrol edge for the spill? into the operative position. The inventionrelates more particularly to pumps of this type employed as injectionpumps for compression ignition internal combustion engines.

- at all times a. maximum area forthe discharge It is the principalobject of the invention to provide a fuel injection pump of an extremelysimple construction in which not only is all interference avoidedbetween 'the incoming' fuel in the suction passages of the pump leadingto the cylinder space and the fuel discharges in the form of spill, bycompletely separating the suction and spill passages, but also whereinunbalanced eddy formations and partial vacuum effects in the workingspace of the pump cylinder are avoided.

A further object of the invention is to ensure passed fuel is employedto assist the discharge action and avoid unregulated swirling, frothingand heating of the spilled fuel.

A still further object is to provide a construction of pump in which thecylinder space can be automatically flushed through with fuel duringthat portion of each cycle of operations of the pump in which fuel isnot being delivered by the pump; in this way the cylinder space ismaintained full of fuel in a very reliable manner and is free frombubbles even when the pump opcrates at very high speeds.

It is to be observed that the avoidance of eddy eifects in the cylinderspace and passages-of a fuel pump are of the greatest importance in connection with modern compression ignition engines due to the fact thatsuch engines operate at relatively high speeds particularly in the caseof transport engines and the fuel pressures employed: amount to anythingfrom 1500 to 5000 pounds per square inch involving enormous speeds oftravel of the fuel in the pump passages and cylinder so that even smalleddy eifects which would not be of material importance when op-' eratingat relatively low speeds, assume a magnitude which can easily mar theaction of the pump to a very serious, extent. Thus the construction ofpumps forming the object of the present invention as specified in theappended claims is of the utmost importance as regards the avoidance ormaterial reduction of the eddy efiects referred to. v

In order that the invention may be fully understood, reference isdirected to the accompanying drawing, in which:

Figure 1 illustrates a fuel pump constructed in accordance with theinvention;

Figure 2 illustrates a vertical section of the upper portionof amodified form ofv fuel pump constructed in accordance with theinvention;

Figure 3 is a section on the line 3-3 of Figure 2, and

Figures 4, 5, 6 and 7 are diagrams illustrating methods of controllingthe spill of pumps constructed in accordance with the invention in amanner hereinafter described.

Referring to Figure 1, a pump is illustrated which comprises a bodymember I within which a cylindrical sleeve or liner 2 is located and islocked in position by a cylinder head 3 which is screwed into the saidbody and within which a compression space .4 is provided. Areciprocatable plunger is slidably mounted within the cylindrical bore 6of the liner 2 and is arranged to be moved in an upward direction forthe delivery stroke by a rotatable cam 1 arranged to bear against aroller 8 mounted upon a cylindrical slide 9 to which the lower end ofthe plunger 5 is secured and which slides in a guideway formed in thebody i; the downward or suction stroke of the plunger 5 is effected by aspring i0 and the plunger 5 is shown in its lower dead centre positionin the drawing. The cam I is of The fuel inlet opening ii in the body Ileads to an annular passage is formed between the said body and theliner 2 and radial passages It in the liner establish communicationbetween the passage l3 and an annular recessi formed in the bore of theliner around the plunger 5. Passages lfi formed in the plunger 5establish a permanent communication between the recess l5 and a bore illformed axially of the plunger and which constitutes the suction passageto the compression space 3. The upper end of the bore ii is closed by avalve E8, the enlarged upper portion of which is arranged to slidewithin the compression space 41 and the valve is normally maintainedupon its seating by a compression spring W-which reacts against the endwall of the compression chamber. Passages 88!: are provided in thebottom of the enlargement of the valve W to enable the fuel to flow fromthe bore E? into the space d upon the upper side of the enlargement. Afuel discharge opening 26 in the head 3 is normally closed by a springcontrolled delivery valve 2! past which fuel is arranged to bedischarged through an-outlet pipe 22.

The upper end of the liner 2 is provided with a recess or pocket 23, thelower edge 25 of which, constitutingthe control edge for the spill isinclined relatively to a plane extending transversely to thelongitudinal axis of the liner. A groove 25 is formed in the peripheryof the plunger 5 in the axial direction thereof, the lower end of whichis in permanent communication with the recess l5 and the upper end ofwhich is arranged to overlap the control edge 25 at a point .spill isdischarged through the recess 23 and groove 25.

It will be appreciated that the suction passage l! in the plunger 5 iscompletely separate from the passages 23, 25 arranged exteriorly of theplunger and through which the spill is discharged, thus entirelyavoiding interference between the spill and the fuel in the said suctionpassage.

Referring to Figures 2 and 3, the same reference numerals have beenemployed where possible for similar parts of the pump as those employedin connection with Figure 1. In this construction the plunger 5 isoperated in a similar manner to that described with reference toFigure 1. The fuel enters the pump through a pipe 82 leading to anannular passage is formed between the body member I and the liner 2 inwhich the bore for the plunger 5 is formed. Passages Id place thepassage is in communication with an annular recess is formed in theliner around the plunger and radial passages I 5 in the plungerestablish communication between the recess l5 and the suction passagell! formed axially of the plunger 5. The upper end of the passage ll isarranged to be closed by a suction valve l8, an upward enlargedextension of which is arranged to slide in the compression chamber i.The downward movement of the valve 18 under the inrluence of its springill is limited by a stop 26 carried by the liner 2 so.that during themovement of the plunger through the lower portion of the suction strokeand the commencement of the delivery stroke, 'the said valve ismaintained 23 in the bore of the liner 2 is arranged to cooperate withthe upper end of a groove 25a formed helically around the plunger 5 forthe purpose of controlling the spill of the pump. The lower end of thegroove 25a is in permanent communication with an annular groove 2!formed in the liner 2 around the plunger and passages 28 arrangedtangentially with respect to the said annular groove (Figure 3)establish communication between the said groove and an annular passage29 formed in the body member I. A passageway 3|! arranged tangentiallywith respect to the passage 29 establishes communica tion between thelatter and an outlet pipe 3| arranged to discharge the spill into thefuel tank or other receiver.

In order that the operation of the pump illustrated in Figure 2 may bereadily appreciated, reference is directed to Figure 5 in which thecurve indicates the plunger movement effected under the control of thecam I; one complete cycle of operation from an initial position atbottom dead centre is indicated by the portion of the curve markedI30I3ila. Assuming the fuel is delivered to the pipe i2 under pressureit flows through the passages 13, iii, l5, l6 and i i into thecompression space 6 during the upward move ment of the plunger until theupper end of the plunger is closed by the suction valve l8 at the pointindicated at E3! in Figure 5, thereafter fuel is delivered past thevalve 2i through the delivery pipe 22 until the upper end of the groove25a meets the control edge 2d at a point, for example, which isindicated at I32 in Figure 5. Thereafter fuel is discharged into therecess 23 and passages 25a, 27, 28, 29 and 30 to the spill outlet 3!during the whole of the remainder of the upward stroke of the plunger.plunger reaches the top dead centre at the point indicated at K33 inFigure 5, the valve it opens under the pressure of the fuel supply andfuel flows through the suction passages past the said valve, through thecompression space 6 and thence through the recess 23, passage 25a and soon out of the outlet 3| until the end of the groove 25a passes thecontrol edge 26 at the point indicated at 835 in Figure 5 when thesuction stroke proper commences and continues to the point 83011. Figure4 shows the various positions of the end of the groove 25a in relationto the control edge 2d at the points corresponding to those indicated inFigure 5; thus bottom *dead centre corresponding to points I30 and i30ais indicated at I20, the point 63! is indicated at I25, the point i32-isindicated at I22 and the top dead centre I33 is indicated at 523.

The cylinder space above the plunger is thus flushed with fuel duringmore than half the period of each cycle of operation of the pump and thepresence of bubbles in the cylinder is avoided. The valve i8 ismaintained open during the downward stroke of the plunger due to theforce of the opposing column of incoming oil and the inertia of thevalve.

The discharge of the spill through the helical groove 25a causes thedischarged fuel to circulate rapidly in the annular passage 21 so thatit is discharged by centrifugal action through the tangentially arrangedpassages 28 into the annular passage 29 in which it again swirls andis"discharged through the passage 30 to the outlet pipe 3! the rapiditywith which the cycles of operation of the pump follow one anothermaintains a constant swirling motion of the discharged fuel in thepassages 21 and 29. The discharge of the As soon as the sufficient toconvey the discharged fuel to the tank, especially where a number ofpumps are embodied in one unit with a discharge opening common to allthe pumps.

As shown in Figure 6, the edge of the helical groove 25a may besemi-circular, the groove being directed at right angles to thecontroledge 24. Itis preferable, however, that the end of the groove should bestraight and parallel to the control edge as shown in Figure 4.

A particularly large passage area is afiorded by the arrangement of thehelical groove as shown in Figure 7, wherein the side of the groove isdis posed parallel to the control edge and the end of the groove'iscurved so as to deflect the fuel easily into the groove.

In Figures 6 and 7, the various positions of the groove 25a for thedifferent positions of the plunger have been indicated by the samereference numerals as in Figure 4.

It is to be understood that in any of the above described constructionsthe recess 23 having the control edge 24 may be provided upon theplunger and the groove 25 or 25a formed in the wall of the cylinderbore', the recess then being inverted and arranged to co-operate withthe lower end of the groove in the cylinder wall.

It will be obvious that where necessary in order to obtain a more rapiddischarge of the spill two or more recesses with inclined control edgesand a corresponding number of grooves in the plunger may be providedevenly spaced around the periphery of the cylinder wall and the plunger.

If only one groove for the discharge of the spill" is provided in theplunger, an additional recess or pocket may be'provided in the cylinderwall opposite to that which co-operates with the said groove and in thiscase the said pocket need not have the inclined control edge although ifsuch an edge is provided it enables the same to spill passages formeddistinct from one another,-

the suction passage being disposed interiorly of said plunger andcommunicating with the exterior of said plunger through at least onelateral suction passage therein, means for closing said suction passageduring-a portion of the stroke of said plunger, said spill passage beingdisposed wholly exteriorly of said plunger and being constituted by onepart formed in the outer surface of said plunger and another part formedin the wall of said cylinder, one of said parts of said spill passagecomprising a groove extending down to a discharge chamber for the spillfuel in.

said plunger and communicating to supply fuel to said suction passageformed interiorly of said plunger through said lateral suction passagetherein, said discharge chamberfor the spill fuel being arranged in saidcylinder wall above said inlet chamber for the fuel supply so as tomaintain the spill fuel entirely separate from the suction fuel and sothat any spill fuel leaking tion stroke,.the combination comprising amain pump body,--a cylinder disposed-within said pump body, a plungerreciprocable in said cylinder, suction and spill passages formeddistinct from one another, the suction passage being disposed interiorlyof said plunger and communicating with the exterior of said plungerthrough at least one lateral suction passage therein, means for closingsaid suction passage during a portion of the stroke of said plunger,saids'pill passage being disposed wholly exteriorly of said plunger andbeing constituted by one part formed in the outer surface of saidplunger and another part formed in the wall of said cylinder, one ofsaid parts of said spill passage comprising a groove extending down toan inner annular discharge chamber for the spill fuel in said cylinderwall, said groove having a closed end cooperating with said another partof the spill passage to control the spill, said another part ofthe spillpassage being in constant communication with the pump chamher, an innerannular discharge chamber for the spill fuel in said cylinder wall intowhich said spill groove is arranged to discharge the spill fuel, aninner annular inlet chamber for the fuel supply also in said cylinderwall and communicating v to supply fuel to said suction passage formedinteriorly of said plunger through said lateral suc tion passagetherein, said inner annular discharge chamber for the spill fuel beingarranged in saidcylinder wall above said inner annular inlet chamber forthe fuel supply, and two outer annular chambers, at least a part of eachof which is formed in said main pump body, said two outer annularchambers being superposed one.

above the other so as to be completely separate from one another andcommunicating the one through a suction passage with said inner annularinlet chamber for the fuel supply and the other through a dischargepassage with said inner annular discharge chamber for the spill fuel,the sealing between the main pump body and the cylinder for the upperedge of the top quter annular spill discharge chamber being effected bythe direct seating of an enlarged portion of the cylinder on a shoulderof the main pump body,

the sealing between the two outer annular chambers being effected by aclose circumferential fit of the cylinder in the main pump body and thesealing-of the lower edge of the lower outer annular inlet chamber forthe supply fuel being effected by means of a packing material compressedbetween a shoulder on the cylinder and the main pump body.

' RUDOLF I.{QRANGE.

